$OpenBSD: patch-src_ptlib_unix_assert_cxx,v 1.1 2017/05/07 20:48:29 espie Exp $
--- src/ptlib/unix/assert.cxx.orig	Fri Apr 28 01:46:38 2017
+++ src/ptlib/unix/assert.cxx	Fri Apr 28 01:46:54 2017
@@ -37,6 +37,7 @@
 #include <ctype.h>
 #include <signal.h>
 #include <stdexcept>
+#include <unistd.h>
 #include <ptlib/pprocess.h>
 
 #ifndef P_BEOS
